1. Field
The present disclosure relates to the fabrication and assembly of microfluidic devices. In particular, a method and apparatus are disclosed wherein the elastomeric layer is a gas-permeable gasket without features.
2. Description of Related Art
Recent developments in the mechanical actuation of microfluidic valves have demonstrated that closing valve membranes against hard surfaces may be more efficient than that against soft surfaces. Most parts of an elastomeric microfluidic device do not need the elastomeric properties (i.e. elasticity, gas permeability, transparency). Some parts may only need chemical inertness, while others may only require transparency. Thus, by decreasing the thickness of the elastomeric layer in a microfluidic device, valve closing by mechanical actuation onto the proximal hard layer is more efficient. Furthermore, it results in a microfluidic device that can withstand higher forces, higher pressures and does not leak. Although devices combining rigid and soft materials have been reported, (Lai, S. M et al. Chem. Commun, 2003, 218-219; Yamamoto, T. et al. Lab Chip, 2002, 2, 197-202) they have not been designed from the standpoint of material requirements and were used in much less demanding applications than radio synthesis
At present, there are several materials that possess properties necessary for microfluidics, however, the curing profile of these materials is such that as soon as it is hard enough to manipulate, the material is already cured past the point at which polymerization of the layers to be bonded could take place. Current methods require several curing steps and not many materials can afford such repeated curing, leaving a limited number of possible materials to use. The most well known methods of microfluidic fabrication rely on molding individual layers and then assembling them together (Psaltis, D. et al. Nature, 2006, 442, 381-386). Microfabrication of elastomeric materials is further complicated by the necessity to handle partially-cured polymer during intermediate steps of the process.
There are several new materials under development that surpass well-known PDMS (polydimethylsiloxane) in their chemical resistance. Use of these materials in place of PDMS will undoubtedly broaden the utility of microfluidics within a range of applications. New materials, however, require the development of novel handling methods that allow precise microfabrication of features in under-cured polymers and layer-to-layer adhesion. These two parameters alone are non-trivial and preclude many new applications in microfluidics.
In view of the present art, what is needed is a microfluidic device that circumvents the complicated and precise microfabrication of features in under-cured polymers as well as the task of layer-to-layer adhesion to provide a microfluidic device that is can be fabricated reproducibly and has utility amongst a range of reaction chemicals, while having a tight seal and being durable.